September 12, 2011

Y chromosome/Language correlations

This is a very small piece (less than 2 pages), but is actually quite useful in order to track various cases where there is a correlation between language and Y-chromosomes. The authors do highlight the interesting case of J2a in India, that I have also blogged about occasionally over the years:

As for the immigrant Indo-European and the presumably indigenous Dravidian languages in India, there is one major candidate genetic marker for immigration from the northwest. It is a Y-chromosome DNA type (J2a) rather than an mtDNA type, and its immigrant status is suggested by its presence at 10 to 20% frequency in high castes, both in Indo-European speakers and farther

south among Dravidian speakers, and its near-absence in lower castes or “tribals” ( 8).

When dealing with language-genetic correlations, we must always be vigilant. In particular the following two points should always be remembered:

Inference that a particular haplogroup existed in early speakers of a language does not mean that it was the only or even dominant haplogroup among them

It does not mean that it was ever exclusive to the speakers of the language either

For example, insufficient phylogenetic resolution may obscure the relationship. This was overcome in the recent Caucasus paper, or the one on J-P58. Another candidate haplogroup, R1a1 has triple peaks among Balto-Slavs, Indo-Aryans, and some Turkic groups, and has also been found in a presumably pre-Slavic European context, and we are slowly beginning to understand its finer-scale structure.

Finer-scale determination of the phylogeny, coupled with historical knowledge and direct typing of ancient DNA remains of historical peoples will surely help inform us more about the ancient origins of common Y-chromosome types.

The highlighted sentence from the abstract below agrees with my own thinking, since even if it is minimal (e.g., in the case of the East Eurasian components in Hungarians and Turks), I know of no case where a people has adopted a new language without even a trace of the patrilineages of the bearers of that language. This is quite useful, as it makes it possible that we may reconstruct some of the patrilineages of the proto-speakers of the language, e.g., in a manner similar to what I did for the case of Tocharian.

Some 6000 different languages are spoken in the world today, and tracing the prehistory of languages and of language change by means of genetic markers has long been a goal (1). However, this has proven to be a more challenging task than simply tracing colonizations. Nevertheless, a number of genetic studies over the past few years have started to address language and language change before recorded history. A correlation is emerging that suggests language change in an already-populated region may require a minimum proportion of immigrant males, as reflected in Y-chromosome DNA types. By contrast, the female lineages, as indicated by mitochondrial DNA (mtDNA) types, do not reflect the survivor language but represent more ancient settlement.

16 comments:

A correlation is emerging that suggests language change in an already-populated region may require a minimum proportion of immigrant males, as reflected in Y-chromosome DNA types. By contrast, the female lineages, as indicated by mitochondrial DNA (mtDNA) types, do not reflect the survivor language but represent more ancient settlement.

We are patriarchal animals. And patriarchy and social practices that result from it such as patrilocality have a strong correlation with conquer/immigrate & marry locals. This is what genetics, history and cultural anthropological studies tell us.

I know of no case where a people has adopted a new language without even a trace of the patrilineages of the bearers of that language.

In many cases, because of the existence of language shifts through processes such as elite dominance and inter-community alliance, over time the Y-chromosomes of the locals overwhelm (may even completely remove at least in theory) those of the conquerors or immigrants among speakers of a language in a specific land that was brought to that land by the conquerors or immigrants.

In the case of J2a though, it appears more as a signal from a pre-IE migration to India from the fertile crescent. J2a is more frequent among southern Indian high-castes, which seems to point at a Dravidian elite (originally coming from the fertile crescent and probably related to Elam) converted to Hinduism at the arrival of Indo-Aryans and conserved their higher status. Otherwise it would be more frequent in the high castes of the North.It would be interesting to know whether J2a is more frequent in Brahuis than among their Indo-Aryan speaking neighbors.

J2a is more frequent among southern Indian high-castes, which seems to point at a Dravidian elite

South Indian upper castes are of North Indian origin, with possible admixture from the locals. There is no reason to think that J2a among them represents any sort of Dravidian element, as it is largely lacking among native Dravidians. Also, the Dravidian theory fails to account for the occurrence of J2a not only in the Indo-Iranian world as a whole (and not just "Elam"), but also well beyond it.

Bah, anyway, personally, I'm not convinced by this neolithic J2a hypothesis about Indo-iranian because Avestan (the earliest known Iranic language) and Sanskrit (the earliest known indo-aryan language) were very close to each other which doesn't seem to corroborate this chronology as these languages were spoken between roughly 1,700 BC - 1,000 BC (works well with the aspect of the Mitanni Indo-iranian words/names of Indo-aryan deities around 1,400 BC) during bronze age (Not even mentionning the tracks of early indo-iranian (some of it clearly from an earlier stage than Rigvedic sanskrit) in Finno-Ugric languages).

That sources finds levels of R1a ranging from 0-26% in the different Iranic groups studied. I see no pattern of Iranic groups having higher R1a levels than their neighbors.

I'm not convinced by this neolithic J2a hypothesis about Indo-iranian

There is no neolithic J2a hypothesis. In fact, the clear social demarcation of J2a in India is incompatible with its arrival prior to the arrival of the Indo-Aryans in the 2nd millennium BC. J2a was almost certainly a major Indo-Aryan lineage in the Indian context, although, as I mention in my post it was neither exclusively Indo-Aryan or the only Indo-Aryan lineage.

"Maybe the resolution is that the settled BMAC were J2a and Indo-Aryans pastoralists were R1a1a, and they went together to India?"

Possibly. But I'm inclined to agree with those that think J2 is pre-Indo-European. It is unlikely that the incoming Indo-Aryans completely exterminated the priestly class. That class is remarkably adept at changing sides so J2 may have been able to preserve a pre-IE dominance.

I dont think we are really seeing a conquering army slaying all the men and taking all the women. If we were we would see more of an autosomal contribution from the invading men. And where we have looked, this does not happen.

Even in patriarchial South America the conquered men lived on as seen in the autosomal genes. There may be a lot of European Y-haplogroups in South America but this is not reflected in the autosomal pool, we do not see 50% Europe.

Rather it seems after the conquest European male lineages may have prospered due to nepotism and selection by local women. If descendants of the conquerors were richer they would be more attractive.

Plus let us not forget some of the other reasons why a male haplogroup might have a tendency to dominate. Male mortality has always been higher than female mortality, even without war. Population growth is not limited by the number of men but by the number of breeding women, one man will do.

Some parts of Asia have a tradition of a group of brothers marrying one wife. Families with few men would not be able to afford a wife. The brothers with a wife have an advantage that translates into wealth in the next generation and on.

Then there is the probably mythological tradition of the Summer King, Harvest King or sacrificial king. A pampered male with many priviledges translatng into many potential offspring, for a while. But at least one bog body (Lindow)fits the profile of a Summer King.

"That sources finds levels of R1a ranging from 0-26% in the different Iranic groups studied. I see no pattern of Iranic groups having higher R1a levels than their neighbors."

Well, I do think there could be. The 0% case is from the Kurmanji-G (from Georgia (Caucasus)) that apparently migrated there only in the 19th century AD and the study states that :

"The Y-chromosome data do suggest that the Kurdish group in Georgia was founded by Kurmanji speakers from Turkey, although the presence of haplogroups P1 and J2 are at unusually high frequencies in the Georgian Kurds, which is an indication of genetic drift, making conclusions based on the Y-chromosome suspect."

the presence of haplogroups P1 and J2 are at unusually high frequencies in the Georgian Kurds, which is an indication of genetic drift

Genetic drift may cause low-frequency variants to go extinct, but if your hypothesis (high R1a in Iranic groups) was correct, then it would be unlikely that R1a would go extinct because of drift (that is unsubstantiated anyway).

Actually, if the P1 (=R2) frequencies are correct, then this provides an immediate link between these Iranic speakers and south central Asia, in agreement also with their possession of "South Asian" autosomal component, and with my theory that the origin of the Indo-Iranian peoples is to be sought in the BMAC.

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